Thermoplastic norbornene resin based optical film

Abstract

A thermoplastic norbornene resin which displays a high degree of toughness, and for which the exhibited retardation and the wavelength dependency of that retardation can be controlled is provided, which is formed from a copolymer with a structural unit represented by a general formula (1) and a structural unit represented by a general formula (2).

1. An optical film comprising at least one resin-layer comprising a thermoplastic norbornene resin formed of a copolymer comprising:
 a structural unit a represented by formula (1) below: 
 
       
         
           
           
               
               
           
         
         wherein, m is 1, p is 0, and the definitions of X and R 1  to R 4  are consistent with the specifically named monomers A as follows:
 8-methoxycarbonyltetracyclo[4.4.0.1 2,5 .1 7,10 ]-3-dodecene, 
 8-ethoxycarbonyltetracyclo[4.4.0.1 2,5 .1 7.10 ]-3-dodecene, 
 8-n-propoxycarbonyltetracyclo[4.4.0.1 2,5 .1 7,10 ]-3-dodecene, 
 8-isopropoxycarbonyltetracyclo[4.4.0.1 2,5 .1 7,10 ]-3-dodecene, 
 8-n-butoxycarbonyltetracyclo[4.4.0.1 2,5 .1 7,10 ]-3-dodecene, 
 8-phenoxycarbonyltetracyclo[4.4.0.1 2,5 .1 7,10 ]-3-dodecene, 
 8-methyl-8-methoxycarbonyltetracyclo[4.4.0.1 2,5 .1 7,10 ]-3-dodecene, 
 8-methyl-8-ethoxycarbonyltetracyclo[4.4.0.1 2,5 .1 7,10 ]-3-dodecene, 
 8-methyl-8-n-propoxycarbonyltetracyclo[4.4.0.1 2,5 .1 7,10 ]-3-dodecene, 
 8-methyl-8-isopropoxycarbonyltetracyclo[4.4.0.1 2,5 .1 7,10 ]-3-dodecene, 
 8-methyl-8-n-butoxycarbonyltetracyclo[4.4.0.1 2,5 .1 7,10 ]-3-dodecene, and 
 8-methyl-8-phenoxycarbonyltetracyclo[4.4.0.1 2,5 .1 7,10 ]-3-dodecene; and 
 a structural unit b represented by formula (2) below: 
 
       
       
         
           
           
               
               
           
         
         wherein, 
         Y represents formula —CH═CH— or formula —CH 2 CH 2 —, 
         R 5  to R 8  each represent, independently, a hydrogen atom, a halogen atom, a substituted or unsubstituted hydrocarbon group of 1 to 30 carbon atoms which may contain a linkage group incorporating any one of an oxygen atom, a nitrogen atom, a sulfur atom, a silicon atom, or a polar group, 
         provided that said groups R 5  to R 8  each exclude a group represented by formula (a) below:
   —(CH 2 ) q —O—C(O)—R′  (a) 
 
         where q represents 0 or an integer of at least 1, and R′ represents an organic group, a plurality of X's present in a molecule of said copolymer being the same or different, and a plurality of Y's present in a molecule of said copolymer being the same or different, wherein the weight ratio (a/b) of said structural unit a to said structural unit b in the copolymer is in the range of 95/5 to 60/40. 
       
     
     
       2. A polarizing plate comprising an optical film according to  claim 1 . 
     
     
       3. The polarizing plate according to  claim 2 , wherein said optical film is present as a protective film formed on at least one surface of a substrate of said plate. 
     
     
       4. The polarizing plate according to  claim 2 , wherein said optical film is present as the substrate of said plate. 
     
     
       5. The optical film according to  claim 1 , which imparts retardation to transmitted light. 
     
     
       6. The optical film according to  claim 5 , comprising at least two said resin-layers laminated together, each of the layers imparting retardation to transmitted light, and wherein the value of the ratio: Re(λ)/λ wherein λ represents the wavelength of transmitted light from said film, and Re(λ) represents the retardation at the wavelength λ, varies over the entire wavelength range from 400 to 800 nm within ±20% of the average value. 
     
     
       7. A method for the production of an optical film as defined in  claim 1 , comprising:
 casting an organic solvent solution containing the thermoplastic norbornene resin of  claim 1  onto a surface. 
 
     
     
       8. The method according to  claim 7 , wherein said organic solvent is a mixed solvent of a good solvent and a poor solvent for said thermoplastic norbornene resin. 
     
     
       9. The optical film according to  claim 1 , wherein, in said formula (2), said groups R 5  to R 8  each represent, independently, either a hydrogen atom or a hydrocarbon group of 1 to 30 carbon atoms. 
     
     
       10. The optical film according to  claim 1 , wherein said copolymer has a glass transition temperature (Tg) of 80 to 350° C. 
     
     
       11. The optical film according to  claim 1 , wherein a solvent content in the or each resin-layer is no more than 10% by weight. 
     
     
       12. The optical film according to  claim 1 , which has a light diffusing function on at least one surface thereof. 
     
     
       13. The optical film according to  claim 1 , which has a transparent conductive layer on at least one surface thereof. 
     
     
       14. The optical film according to  claim 1 , which has an antireflective layer on at least one surface thereof. 
     
     
       15. The optical film according to  claim 1 , wherein the monomer B of structural unit b is a compound selected from the group consisting of:
 bicyclo[2.2.1]hept-2-ene, 
 5-methylbicyclo[2.2.1]hept-2-ene, 
 5-ethylbicyclo[2.2.1]hept-2-ene, 
 5-methoxycarbonylbicyclo[2.2.1]hept-2-ene, 
 5-methyl-5-methoxycarbonylbicyclo[2.2.1]hept-2-ene, 
 5-phenoxycarbonylbicyclo[2.2.1]hept-2-ene, 
 5-methyl-5-phenoxycarbonylbicyclo[2.2.1]hept-2-ene, 
 5-cyanobicyclo[2.2.1]hept-2-ene, 
 5-ethylidenebicyclo[2.2.1]hept-2-ene, 
 5-phenylbicyclo[2.2.1]hept-2-ene, 
 α form of 5-(2-naphthyl)bicyclo[2.2.1]hept-2-ene, 
 β form of 5-(2-naphthyl)bicyclo[2.2.1 ]hept-2-ene, 
 5-fluorobicyclo[2.2.1]hept-2-ene, 
 5-fluoromethylbicyclo[2.2.1]hept-2-ene, 
 5-trifluoromethylbicyclo[2.2.1]hept-2-ene, 
 5-pentafluoroethylbicyclo[2.2.1]hept-2-ene, 
 5,5-difluorobicyclo[2.2.1]hept-2-ene, 
 5,6-difluorobicyclo[2.2.1]hept-2-ene, 
 5,5-bis(trifluoromethyl)bicyclo[2.2.1]hept-2-ene, 
 5,6-bis(trifluoromethyl)bicyclo[2.2.1]hept-2-ene, 
 5-methyl-5-trifluoromethylbicyclo[2.2.1]hept-2-ene, 
 5,5,6-trifluorobicyclo[2.2.1]hept-2-ene, 
 5,5,6-tris(trifluoromethyl)bicyclo[2.2.1]hept-2-ene, 
 5,6,6-tetrafluorobicyclo[2.2.1]hept-2-ene, 
 5,5,6,6-tetrakis(trifluoromethyl)bicyclo[2.2.1]hept-2-ene, 
 5,5-difluoro-6,6-bis(trifluoromethyl)bicyclo[2.2.1]hept-2-ene, 
 5,6-difluoro-5,6-bis(trifluoromethyl)bicyclo[2.2.1]hept-2-ene, 
 5,5,6-trifluoro-6-trifluoromethylbicyclo[2.2.1]hept-2-ene, 
 5-fluoro-5-pentafluoroethyl-6,6-bis(trifluoromethyl)bicyclo[2.2.1]hept-2-ene, 
 5,6-difluoro-5-heptafluoro-iso-propyl-6-trifluoromethylbicyclo[2.2.1]hept-2-ene, 
 5-chloro-5,6,6-trifluorobicyclo[2.2.1]hept-2-ene, 
 5,6-dichloro-5,6-bis(trifluoromethyl)bicyclo[2.2.1]hept-2-ene, 
 5,5,6-trifluoro-6-trifluoromethoxybicyclo[2.2.1]hept-2-ene, 
 5,5,6-trifluoro-6-heptafluoropropoxybicyclo[2.2.1]hept-2-ene, 
 5-(4-phenylphenyl)bicyclo[2.2.1]hept-2-ene, and 
 4-(bicyclo[2.2.1]hept-5-en-2-yl)phenylsulfonylbenzene.